Certain wavelengths seem to trigger the lux meter more then others and the high CRI LED’s have a wider range of wavelengths so they read differently then the equivalent 70cri LED. Although it is hard to get exact numbers since you rarely see the same bin in both 70cri and 90cri.
It makes sense though when you think about it, it is the same reason CW reads higher then NW. Different wavelengths triggering the sensor differently.
Although as a basic rule of thumb you can add/subtract a few percent to get closer.
S2+ (1329)
282 lumens at 30 sec. on TA tube
286 lumens at 30 sec. maukka calibration report
Difference ~ 1.40% (rounded to 3 sig figs) ± .01% (uncertainty)
My BLF348 (1129)
57 lumens at 30 sec. on TA tube
57.2 lumens at 30 sec. maukka calibration report
So, I need some confirmation on my NW numbers. Reference numbers in yellow.
Does it make sense that the multiplier should be higher for the CW than the neutral? For some reason, I was thinking it would be the other way. Everyone says CW read higher, which makes me think I would need a lower multi for them, to bring them down.
Using a Dr Meter LX1330B in my sphere.
Getting an average of 0.1994 for the NW and 0.2081 for the CW.
The convoy light is very consistent with different battery voltages and light head temperature (back to back tests). The 348 is a bit more sensitive to the voltage and more so with the temperature (back to back tests always show lower numbers).
Do I keep digging or call it good?
Maukka, what voltage are your eneloops when you install to test? right off the charger (I get about 1.51v) or rested (I get 1.38v that way).
I also graphed (linear) the difference across color temps I have on hand. I’m hoping the linear relationship is a good way to go. Way easier with just two data points.
I test with the Eneloops right off the charger (within 20 minutes usually). I would think that the voltage drop when the light is turned on will be much larger than letting them rest for a couple of hours. That’s why I included the 60s number. The light temperature will have a bigger effect than the battery voltage, since the output drops very rapidly at the beginning but not at all after the temperature has settled even though voltage keeps dropping.
It seems your readings are very stable between different tests.
Meters react very differently to different wavelenghts as djozz’s latest lux meter test shows. For example, the noname LX-1330B reads 7.5% low on the 4500K 70 CRI Supwildfire Mitko thrower and 3% high on the 4000K 90+ CRI Sofirn SP33 compared to a good meter.
Awesome. Thank you. I’ll call these results good, based on this particular dr meter. I’ll just re-run calibration every once in a while to make sure the sphere is reading what I expect.
Nicest part is now that I have your calibrated test lights, I can grab a better meter, down the road, and recalibrate accordingly.
These test lights are really a game changer for the entire hobby. Thanks again for offering them.